The United States Naval Observatory (USNO) produces GPS-based estimates of satellite orbits, satellite- and receiver-clock time corrections, and earth-orientation parameters five times per day: once in a daily “rapid” process, the results of which are available with approximately 16-hour latency, and four times in an every-six-hours “ultra-rapid” process, the results of which are available with 3-hour latency. The rapid products supply 24 hours of post-processed estimates; the ultra-rapid… CONTINUE READING